1. Technical Field
The present invention relates generally to mattresses, and more particularly to sleeper sofa mattresses of the type having a spring assembly and an overlying top cushion.
2. Discussion
Sleeper sofa mattresses are designed to be extended flat to provide a sleeping surface and to be folded for storage within a sofa. Folding of the mattress for storage generally involves doubling over one or more parts of the mattress, thereby providing a substantially flat surface for the placement of sofa seat cushions thereupon. This folding of the mattress is often accompanied by a bunching of the padding assembly, including bunching of the covering and/or additional padding located within the padding assembly. This bunching typically takes place across several random and irregular transverse flexure lines which are created because of the inability of multiple layers of padding and covering materials to be fixedly secured to each other at incremental locations along the length and width of the mattress. Bunching may also occur where the mattress covering and/or padding members may become retained within the folds of a spring assembly, causing an inability to completely compress the folds.
Bunching of the mattress covering and/or padding members may result in increased difficulty in folding the mattress, and may also result in a tendency for the mattress to retain a portion of the folded shape when extended flat. This is due at least in part to the shifting of the padding and covering materials relative to each other in a lengthwise direction along the mattress. This bunching and shifting may additionally reduce the sofa's seating comfort, and, over time, a deterioration in the condition of the mattress at or around the folding locations may shorten the useful life of the mattress.
The need therefore exists for an improved method for securing multiple layers of a composite mattress assembly in a fixed relative relation at incremental locations along the length of the mattress assembly so that a folding of the mattress may be conveniently accomplished without bunching and shifting of the mattress components. The need also exists to reduce the tendency of the mattress to retain a portion of its folded shape when extended flat.